The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
A diesel engine produces particulates that are typically filtered from exhaust gas by a diesel particulate filter (DPF). The DPF is disposed in an exhaust system of the diesel engine. Over time, the DPF becomes full and trapped diesel particulates of the DPF must be removed. A regeneration process is performed to remove the particulates. The regeneration process ignites the particulates to initiate an exothermic reaction that propagates along the DPF.
Fuel may be injected into a cylinder of a diesel engine during a combustion cycle and after ignition of a compressed air/fuel mixture. The injected fuel, referred to as post-injected (PI) fuel, may be introduced in ignition and/or exhaust strokes of the combustion cycle. The unburned PI fuel exits the diesel engine with the exhaust gas and may be combusted by an oxidation catalyst disposed in the exhaust system. The heat released by the combustion in the catalyst increases the temperature of the exhaust system, which facilitates the ignition of the DPF particulates. During certain conditions, the regeneration process can cause visible white smoke, which is known as hydrocarbon (HC) break-through.